Open Paleo

Sarmientosaurus

Martínez et al., 2016 sahr-me-en-toe-sor-us

Named after the town of Sarmiento in Chubut Province, Argentina, near where the fossils were discovered, combined with Greek 'sauros' (lizard).

100.5–89.8 million years ago Cenomanian–Turonian, Late Cretaceous
Late Cretaceous stages

Sarmientosaurus is a genus of titanosaurian sauropod dinosaur belonging to the Titanosauria. It lived in what is now South America, specifically Argentina, during the Upper Cretaceous Period about 95 million years ago. The type species is Sarmientosaurus musacchioi.

Under dispute

Sarmientosaurus was originally described as a basal lithostrotian titanosaur (Martínez and colleagues, 2016), but recent analyses instead place it within Diamantinasauria — recovered in a polytomy of diamantinasaurians by Poropat and colleagues (2023), and as the earliest-diverging member of the clade by Beeston and colleagues (2024). The position of Diamantinasauria relative to Titanosauria is treated in the clade entry.

Diagnosis

  1. Maximum diameter of orbit nearly 40% rostrocaudal length of cranium
  2. Complex maxilla-lacrimal articulation with ascending ramus embedded in lacrimal dorsal process
  3. Medial edge of maxillary ascending ramus bordering bony nasal aperture with low but well-defined ridge
  4. 'Tongue-like' ventral process of quadratojugal overlapping quadrate caudally
  5. Separate foramina for all three branches of trigeminal nerve
  6. Absence of median venous canal connecting infundibular region to ventral brainstem
  7. Middle cervical vertebrae with 'strut-like' centroprezygapophyseal laminae
  8. Extremely elongate and slender ossified tendon extending along cervical series ventrolateral to vertebrae and ribs

Species

Sarmientosaurus musacchioi Martínez et al., 2016

Type species

Named for Eduardo Musacchio, an educator at the Universidad Nacional de la Patagonia San Juan Bosco, in recognition of contributions to Patagonian paleontology.

Holotype
MDT-PV 2 , Museo Desiderio Torres-Paleovertebrados
Material
Nearly complete skull with partial axis, third cervical vertebra, fragments of fifth cervical vertebra, nearly complete sixth cervical vertebra, partial seventh cervical vertebra, and section of ossified cervical tendon
Horizon
lower Bajo Barreal Formation, Cenomanian–Turonian, Late Cretaceous , 100.5–89.8 million years ago
Locality
Estancia Laguna Palacios, Chubut, Argentina

References

  1. Martínez, R. D. F.; Lamanna, M. C.; Novas, F. E.; Ridgely, R. C.; Casal, G. A.; Martínez, J. E.; Vita, J. R.; Witmer, L. M. (2016). A Basal Lithostrotian Titanosaur (Dinosauria: Sauropoda) with a Complete Skull: Implications for the Evolution and Paleobiology of Titanosauria. PLOS ONE 11(4): e0151661. Public Library of Science (PLoS). doi:10.1371/journal.pone.0151661 martínez2016a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates, and the appearance features.

    jones2026b
  3. Poropat, S. F.; Mannion, P. D.; Rigby, S. L.; Duncan, R. J.; Pentland, A. H.; Bevitt, J. J.; Sloan, T.; Elliott, D. A. (2023). A nearly complete skull of the sauropod dinosaur Diamantinasaurus matildae from the Upper Cretaceous Winton Formation of Australia and implications for the early evolution of titanosaurs. Royal Society Open Science 10(4): 221618. doi:10.1098/rsos.221618

    Recovered Sarmientosaurus within Diamantinasauria, in a polytomy with the Diamantinasaurus specimens and Savannasaurus.

    poropat2023a
  4. Beeston, S. L.; Poropat, S. F.; Mannion, P. D.; Pentland, A. H.; Enchelmaier, M. J.; Sloan, T.; Elliott, D. A. (2024). Reappraisal of sauropod dinosaur diversity in the Upper Cretaceous Winton Formation of Queensland, Australia, through 3D digitisation and description of new specimens. PeerJ 12: e17180. PeerJ. doi:10.7717/peerj.17180

    Recovered Sarmientosaurus as the earliest-diverging member of Diamantinasauria.

    beeston2024a